Dating dinosaurs and other fossils - Australian Museum
"Accelerator mass spectroscopy can be used to carbon date bones, wood fossil fuels from other sources of carbon dioxide in the atmosphere. I understand the confusion. You need to understand the biological and chemical processes that go on to understand why it works. As something dies, a process. Seventy years ago, American chemist Willard Libby devised an ingenious method for dating organic materials. His technique, known as carbon.
A number of processes could cause the parent substance to be depleted at the top of the magma chamber, or the daughter product to be enriched, both of which would cause the lava erupting earlier to appear very old according to radiometric dating, and lava erupting later to appear younger.
Other possible confounding variables are the mechanisms that can alter daughter-to-parent ratios. We can see that many varieties of minerals are produced from the same magma by the different processes of crystallization, and these different minerals may have very different compositions. It is possible that the ratio of daughter to parent substances for radiometric dating could differ in the different minerals.
Clearly, it is important to have a good understanding of these processes in order to evaluate the reliability of radiometric dating. Other confounding factors such as contamination and fractionation issues are frankly acknowledged by the geologic community, but are not taken into consideration when the accuracy and validity of these dating methods are examined. The following quotation from Elaine G.
Kennedy addresses this problem. Contamination and fractionation issues are frankly acknowledged by the geologic community. For example, if a magma chamber does not have homogeneously mixed isotopes, lighter daughter products could accumulate in the upper portion of the chamber.
If this occurs, initial volcanic eruptions would have a preponderance of daughter products relative to the parent isotopes. Such a distribution would give the appearance of age.
As the magma chamber is depleted in daughter products, subsequent lava flows and ash beds would have younger dates. It does suggest at least one aspect of the problem that could be researched more thoroughly. The problems inherent in radiometric dating often cause them to be so unreliable that they contradict one another rather than validating each other.
How Carbon-14 Dating Works
It would really be nice if geologists would just do a double blind study sometime to find out what the distributions of the ages are. In practice, geologists carefully select what rocks they will date, and have many explanations for discordant dates, so it's not clear how such a study could be done, but it might be a good project for creationists. There is also evidence that many anomalies are never reported. There are so many complicated phenomena to consider like this that it calls the whole radiometric dating scheme into question.
Only then can you gauge the accuracy and validity of that race. We need to observe when the race begins, how the race is run are there variations from the course, is the runner staying within the course, are they taking performance enhancing drugs, etc. All bases must be covered if we are going to accurately time the race. This is the major flaw in radiometric dating, e.
Dating a Fossil - Carbon Dating | HowStuffWorks
Secondly, you must have an observable time span so we can be certain nothing has affected the amount of the radioactive element being measured, e. Finally, we need to be certain about the end or finish point. This is some finite point in the future.
Unfortunately, humans are on the verge of messing things up. The slow, steady process of Carbon creation in the upper atmosphere has been dwarfed in the past centuries by humans spewing carbon from fossil fuels into the air.
Since fossil fuels are millions of years old, they no longer contain any measurable amount of Carbon Thus, as millions of tons of Carbon are pushed into the atmosphere, the steady ratio of these two isotopes is being disrupted. In a study published last yearImperial College London physicist Heather Graven pointed out how these extra carbon emissions will skew radiocarbon dating.
Thanks to Fossil Fuels, Carbon Dating Is in Jeopardy. One Scientist May Have an Easy Fix
Although Carbon comprises just over 1 percent of Earth's atmosphere, plants take up its larger, heavier atoms at a much lower rate than Carbon during photosynthesis.
Thus Carbon is found in very low levels in the fossil fuels produced from plants and the animals that eat them. In other words, burning these fossil fuels dwarfs the atmospheric levels of Carbon, too.
By measuring whether these levels of Carbon are skewed in an object being radiocarbon dated, future scientists would be able to then know if the object's levels of Carbon have been skewed by fossil fuel emissions. Researchers could then disregard the date and try other methods of dating the object. This uses radioactive minerals that occur in rocks and fossils almost like a geological clock.
So, often layers of volcanic rocks above and below the layers containing fossils can be dated to provide a date range for the fossil containing rocks. The atoms in some chemical elements have different forms, called isotopes. These isotopes break down at a constant rate over time through radioactive decay. By measuring the ratio of the amount of the original parent isotope to the amount of the daughter isotopes that it breaks down into an age can be determined.How Do Paleontologists Date Fossils?
We define the rate of this radioactive decay in half-lives. If a radioactive isotope is said to have a half-life of 5, years that means after 5, years exactly half of it will have decayed from the parent isotope into the daughter isotopes.
Dating Sedimentary Rock - How Do Scientists Determine the Age of Dinosaur Bones? | HowStuffWorks
Then after another 5, years half of the remaining parent isotope will have decayed. While people are most familiar with carbon dating, carbon dating is rarely applicable to fossils. Carbon, the radioactive isotope of carbon used in carbon dating has a half-life of years, so it decays too fast.
It can only be used to date fossils younger than about 75, years.